It's probably not so unusual for a man (or woman) to feel confused after making a big committment. Big committments can be scary even when we know we've made the right choice (ie: getting engaged). You've asked how can I get him to stay with me. Firstly, remember that he's already committed to you, above all others, so try not to freak out too much, and just express your feelings honestly when you're feeling calm and he is too. You can't force someone to stay with you because you would only end up both being unhappy, the engagement is about the love between the two of you, you need to remind him how happy he makes you and how much it means to you, and how frightened you feel when he feels confused and you don't. Good communication now will hopefully lead to good communication in the future, best wishes!